1. Field of the Invention
This invention relates to the management of overload situations in computer-based server systems.
2. Description of the Related Art
Certain types of servers, e.g. directory servers or message servers, perform basic operations which are known in advance, both in number and nature. The average time needed for each task the server may perform is known in advance, at least approximately. Thus, servers of that type have predictable performance rating. In such servers, a potential overload situation may be anticipated by observing the number and/or nature of the requests that the server receives. This may be called “intrinsic overload management”, referring to the fact the overloads are managed from the traffic of requests itself.
Other servers do not have predictable performance rating in that it is generally not possible to foresee a potential overload from the flow of incoming requests. Examples of such servers are application servers and portal servers: in an application server, the time needed for the server to execute a given application may vary considerably; in a portal server, the time needed to render a given web page available is also much variable, depending upon the number and nature of the channels being contained in that page. Such servers in fact “aggregate” a variable number of individual tasks. Thus, an “intrinsic overload management” is generally not feasible and/or not satisfactory.